The present invention relates to a tilt steering device which is operable by an electric motor for use in motor vehicles and the like.
Conventional tilt steering devices of the type mentioned include those which comprise a bracket fixed to the body of a vehicle, a tilt bracket pivoted to the fixed bracket, and a tilting electric motor mounted on the fixed bracket for pivotally moving the tilt bracket with its rotation. A lower steering shaft is supported by a lower column on the fixed bracket, and an upper steering shaft by an upper column on the tilt bracket. The lower steering shaft is connected to the upper steering shaft by a universal joint, the center of which is positioned on the center line of the pivot for supporting the tilt bracket. A steering wheel is attached to the upper end of the upper steering shaft. The motor, when driven, pivotally moves the tilt bracket, thereby shifting the steering wheel.
With the tilt steering device described, it is required to reduce the speed of rotation of the motor and further convert the rotation to the pivotal movement of the tilt bracket. Conventionally, gears are used for the speed reduction. The gear reduction means therefore gives off a great noise and has the problem that the gears and other components must be prepared with high precision. Moreover, there is the problem that when the steering wheel is loaded, the force is transmitted to the drive side to reversely rotate the motor.